Railway freight wagons are supported by a railway bogie. Referring to the prior art arrangement shown in FIGS. 1, 2 and 3 of the present specification, the bogie 10 includes a pair of sideframes 12 spaced apart by a bolster onto which the wagons are mounted. Opposing ends 14, 16 of each bogie sideframe 12 are arranged for mounting to an axle of a wheelset 8 via an inverted U-shaped adapter bushing 18 which in turn supports a bearing 20. Each adapter bushing 18 is seated on an upper side region of a respective bearing 20 and is also fastened to a respective sideframe end 14, 16 so that the bearing 20 cannot move longitudinally or laterally out of alignment when the rail wagon is in motion. The adapter bushing 18 is located in a corresponding U-shaped cut-out 22 of the sideframe end 14, 16, the U-shaped cut-out 22 defined by two pedestal legs 24, 26. The bearings 20 for the axles are located at the distal ends of each axle on an in use outermost side of the sideframe 12, and a respective wheel 8 is positioned on an in use innermost side of each sideframe 12.
In the prior art configuration shown in FIG. 1, the inner pedestal leg 24 of the sideframe 12 comprises two generally elongate and parallel side walls 30, 32 with a generally horizontal flange 34 extending therebetween to form a saddle, and it is onto the flange 34 which the known axlebox retainer key 36 is seated and fastened. The axlebox retainer key 36 is shown as a basic rectangular prism with one generally tapering end shaped as a tang 28 having a flat uppermost face portion 38 thereon. The key 36 is positioned between the parallel side walls 30, 32 of the pedestal leg 24 so as to protrude some distance in a direction toward the bearing 20. The face portion 38 of the key 36 is arranged to be approximately tangential to, and located a small clearance from, a periphery of the bearing 20. The key 36 is fastened to the horizontal flange 34 of the pedestal leg 24 using a bolt 40 located in a through-hole 42 in the flange 34, and the bolt 40 is fastened by a nut 44, as can be seen in the prior art FIGS. 1, 2 and 3.
In use, when rail wagon and bogie 10 are lifted up (for example when lifted by a crane, or when being lifted for subsequent inversion for dumping any bulk contents of the wagon) the wheelset 8 must also be lifted therewith. The four axlebox retainer keys 36 on a bogie 10 (ie. two on each sideframe 12 in a pair of sideframes) restrain the bearings 20 (and therefore the wheelset 8 and axle) from falling under the influence of gravity out of the U-shaped cut-out 22 of the sideframe 12. When the rail wagon is lifted, the bearing 20 will move under the weight of the wheelset 8 and axle to rest against the uppermost face portion 38 of the axlebox retainer key 36, and no further downward movement of the axle and wheelset 8 can then occur.
There are normally four axlebox retainer keys 36 for each bogie. During maintenance, which is typically necessary sometime after 9 to 36 months in service depending on the wheel wear rate, all of the keys 36 need to be removed to free the wheelsets 8 for re-profiling of the tread contour. Normally this accomplished by the use of tools such as a spanner or an impact gun to loosen off the nut 44. The access to the nut 44 is from directly underneath the sideframe 12, which can result in lower back strain and sore knees for a maintenance worker, especially if that worker is required to handle up to 10 or 20 wagons a day in a single shift at a maintenance workshop.
In addition, the mounting bolt arrangement is not dependable because the vibrations associated with normal operation of the bogie can work the nut loose and allow the bolt to pop out. The key then easily falls out when the bolt is gone.